Certainly as Rooster suggested above, West of Safety Bay road may be considered the prime streets in Shoalwater.
However, recent changes to the R codes in Western Australia mean that there are some excellent investment opportunities East of Safety Bay road that still carry the Shoalwater address - and hence the associated value.
Basically, starting at Arcadia Drive on the coast, real estate values drop as you move inland, street by street.
A few 'choice ' streets maybe Gloucester Cres, Fifth Ave and Churchill Ave.
Some of the streets that run off Arcadia Drive are very highly sought after also.
There are a few pockets of Shoalwater that you may wish to avoid but over all it's a very well regarded suburb.